Cylinder Power Balance Test
A Cylinder power balance test tests the power of each cylinder, testing its effectiveness compared to the others. The test is best performed with an engine analyzer. If an analyzer is unavailable, the power (connector) from the cylinder's injector or coil can be momentarily (a few seconds) disconnected. The wire from its corresponding spark plug or distributor connection can be removed to disable the desired cylinder. This depends on the type of engine. Check with manufacturer’s specifications before removing the spark plug boot and remember safety first. A prolonged open in the secondary ignition system may cause damage to the coil or ignition module. The test is performed to locate the cylinder causing a misfire or not contributing to the engine balance and performance.
Use a grabber or a tool that will protect your hand from the shock that may result from removing the plug cover. Some coil packs produce more than 35K volts.
Notice the rpm drop as the cylinder is disabled. If a cylinder’s drop is not consistent with the others, this indicates a problem with that cylinder. An engine analyzer tests each cylinder and then compares the results. The reasons for a cylinder not contributing include an ignition problem, fuel delivery, or a mechanical problem such as a faulty valve or worn piston rings.